Polyimide and polybenzoxazole resins have excellent heat resistance, electrical insulation properties, and mechanical characteristics. Accordingly, they have been widely used for surface protective films of semiconductor devices, interlayer dielectric films, insulating layers of organic electroluminescent elements, etc.
In the case where a polyimide or polybenzoxazole resin is used as a surface protective film or an interlayer dielectric film, as a method for forming through holes, etc., etching using a positive photoresist can be mentioned. However, this method has a problem in that the process includes applying and stripping a photoresist and thus is complicated. Thus, for the purpose of rationalizing the operation process, heat-resistant materials having photosensitivity have been examined.
For example, as positive-working photosensitive heat-resistant compositions that can be developed with an aqueous alkali solution, a composition containing a polyamic acid ester having a phenolic hydroxyl group and an o-quinonediazide compound (Patent Document 1), a composition containing a solvent-soluble, closed-ring polyimide and a naphthoquinonediazide compound (Patent Document 2), and a composition containing a polybenzoxazole precursor and a naphthoquinonediazide compound (Patent Document 3) have been reported.
However, in recent years, with the increase in wafer size, device downscaling, and the increase in package density, speed, and capacity, there have been increasing demands for interlayer dielectric films having high sensitivity applicable to multilayer interconnection.
In response to these requirements, in order to improve the solubility in a developing solution and the transparency, it has been examined to increase the sensitivity of a polyamic acid resin by using an alicyclic structure (Patent Documents 4 and 5) or a phenolic-hydroxyl-group-containing diamine having an electron-withdrawing hexafluoropropyl group or sulfonyl group (Patent Documents 6 and 7).